This invention relates to an industrial robot system operated under program control and capable of switching over to an earthquake mode control at the occurrence of an earthquake.
An example of an industrial robot is disclosed in the published Japanese Patent Application Publication No. 55-21362. The manipulator arm corresponds to a workpiece conducting a continuous motion, and is operatively controlled according to a series of program steps.
The industrial robot as stated above has the problem that, when an earthquake has occurred, variations in an electric current due to vibrations will result in abnormal operation, triggering accidents such as the collision of the industrial robot against another device disposed in the surroundings.